关键词: &alpha, &alpha, -二乙酰基二苄硫缩烯酮, 脱乙酰基, 缩合

Abstract: The behavior of α,α-diacetyl ketene dibenzylthioacetal 1a under basic conditions was studied. Catalyzed by steric hindered base ast-BuONa(int-BuOH), α-acetyl ketene dibenzylthioacetal 2a could be obtained in 98% yield within 3 min via deacylation of 1a. Assisted byt-BuONa(int-BuOH), α-cinnamoyl ketene dibenzylthioacetals were produced in high yields by reacting both 1a and 2a with arylaldehydes; whereas, under the same conditions, the corresponding α,α-dicinnamoyl ketene dibenzylthioacetals 4 were formed when furan-2-carbaldehyde and thiophene-2-carbaldehyde were used asthe electrophiles. These evidences support the proposed mechanism that, catalyzed byt-BuONa (int-BuOH), the reaction of 1a with arylaldehydes may normally proceed via a sequential deacylation-condensation process and the formation of double condensation products 4 may be due to the higher activity of furan-2-carbaldehyde and thiophene-2-carbaldehyde under the selected reaction conditions.

Key words: α,α-Diacetyl ketene dibenzylthioacetal, Deacylation, Condensation